Automatic tracking mechanism



March 16, 1954 R. M. RINGOEN AUTOMATIC TRACKING MECHANISM Filed NOV. l5, 1952 UNITED STATES .PATENTOFFICE AUTOMATIC TRACKING MECHANISM Richard M. Ringoen, Cedar Rapids, Iowa, assignor Y to Collins Radio Company, Cedar Rapids, Iowa, a corporation of Iowa Application November 15, 1952, Serial No. 320,692

This invention relates in general to detecting means and in particular to an automatic cloud tracker.

Conventional radiometric detection compares the antenna temperature to a phase reference temperature of approximately 325 degrees Kelvin. The antenna temperature when pointed at the atmosphere is generally between 20 and 50 degrees Kelvin, which requires that the diierence between this temperature and the reference temperature be nullified in the receiving system. Another drawback of the conventional type radiometer is that it does not lend itself to automatic positioning of the antenna on the center of the cloud or 7 Claims. (Cl. 343-117) An antenna is designated generally as I and comprises a focusing disc I I which has a wave guide I2 mounted at its focal point and which supplies an inputto a lead I3. The antenna I0 is supported on a yoke I 4 which has a horizontal or elevation axis I5 and a vertical or azimuth axis I6.

'I'he lead I3 supplies an input to a radiometric receiver designated generally as I1 and which comprises a .balanced radio frequency mixer I8 that receives the incoming signal and an input from a local oscillator I9. An intermediate frequency amplifier 2| receives the output of the mixer I8 and a second detector 22 receives the other targets. To detect a cloud the antenna output of the amplifier 2I to remove the audio beam must be scanned over a wide angle and signal therefrom. Al tuned. audio pre-amplifier the change in output with antenna position ob- 23 receives the output of the seconddetector to served. 'I'his limits the amount of integration amplify it.

which may be used in the output presentation. A second tuned audio amplifier 24 receives the Another disadvantage is that considerable atoutput of the receiver I1 and raises it to a higher tention must be given to the equipment by an oplevel. l erator. He must carefully check the tuning of The axis I6 is connected to the output shaft of the receiver and readjust the nullifying signal a differential 26` which receives an oscillatory infrom time to time. Constant surveillance is reput from a shaft 2'I that is connected to a rocker quired by the operator. arm 28 which has its free end connected to a link It is an object of this invention, therefore, to 29. The opposite end .of the link 29 is connected provide a radiometric tracking system which does to a wheel 3| that is rotatably supported on a not utilize an arbitrary thermal reference signal. shaft 32. The shaft 3.2 is driven by a scanning Another object of this invention is to provide motor 33. p `an automatic tracking system which searches a 3o The shaft 32 is also connected to a one to two relatively broad sector until a target is noted withgear box which is connected to a two-phase in the sector, at which time it changes to a narreference generator 34 which has a pair of out- IOW angle Scanning Operatnput leads 36 and 3'I, respectively, that are con- Another object of this invention is to provide an I nected, respectively, to phase detectors 38 and 39. automatic tracking device wherein the antenna is 35 The phase detectors 38 and 39 also receive inputs scanned over a relatively small angle. from the tuned audio amplifier 24.

A feature of this invention is found in the pro- An integrating network'dl receives the output vision for a radiometric receiver which khas its of the phase detector 39 and furnishes an 'output antenna connected to a scanning motor, which is to an amplitude meter 42. in turn connected to a two-phase reference gen- 40 A direct current amplifier and integrator 43 erator that supplies inputs to a pair of phase dealso receives an input from the integrating nettectors that also receive the output of the radiowork 4I and has output leads 44 and 45 connected metric receiver. One of the phase detectors proto an electromagnetic relay 46 which controls the duces an output which is proportional to the am' position of a switch 4l between contacts 48 and plitude of the. target radiation and the second 4 l, I phaseV detector produces an output proportional The output of the phase detector 138 is supplied to the tracking error. `A tracking motor is conto a second integrating network 5I which is electrolled by the .tracking error signal tokeep the trically connected to the contact 4.9. A vsector antenna on target. f scan signal generator 52 is connected electrically Further features, objects and advantages of 50 to the contact 48 and a Contact 53 is connected this invention will become apparent from the folelectrically to the switch 4l, A contact 54 is lowing description and claims when read in view mounted 'adjacent the contact`53 an'djis connected of the'drawn'g in which the Iigureillustratesan to a manual control' 5.6.` Q 1i i .f automaticl tracking mechanism' according'to the 'A switch' 5l' is movable.' between the .contacts present'inv'ention. 55 53 and 54 and is electrically connected 'to"a"`s'ervo amplier 58 which supplies an electrical input through lead 59 to a servo tracking motor 6I. The servo tracking motor El has an output shaft 62 which supplies an input to the differential 26 and which is also connected to a single speed synchro generator 63. The synchro generator 63 has three-phase outputs which are connected, respectively, to the leads 54, 65 andr 66 that arein turn connected to a single speed synchro motor 61.

The synchro motor 61 has an output shaft 63 which is in turn connected to an azimuth indicator 69.

In operation, scanning motor 33 continually rotates at a fixed speed, asfor example, 21/2 revolutions per second. The Agearing .between the scanning motor 33 and the shaft I6 may be such that the scanning motor causes the `shaft IE to oscillate over a degree sector. vIn the event that the antenna l0 is pointed toward a radiating body which is smaller than the angle of scan, the received vsignal Will Ihe ,modulatedat alive cycle v,per second rate, which is `two times '.the revolutions .per second ofthe scanning motorSS. ,Thisfis because the "antenna willsweep past the target twice for each revolution of the ,shaft 3,2. .Themodulated input from the antenna .Will be fed by the lead i3 to the receiver Where the` audio modulation resultingfrom .a target Withinthe scanarea will be removedandpied tothe tuned audioamplierlli.

TheV vtwo-'phase reference generator 34 has.v its armaturerotated at twicelthe speed of the shaft 32 because of the actionof the oneto two .gear .box,35. l'Ihe referencegenerator 34 producesa vpair ofisinus'oidal outputs Ywhich are ninetydegrecs out .ofph'ase The lead -31 supplies one .of the reference signals from the generator 34 to the phasef detector 39 andwhen the output of thetuned-audio amplier is .compared With the Y.output l,arriving through the lead 31 the phase detector4 39 will produce anoutput proportional to the amplitude `of the incoming, signal. lForexample, sup- .pose the ,antenna l.0 is scanningacrossa target ,which is radiating energy that is `receivedas the .antennaisscanned la`. crossthe target. The amplitudel of this energy Ywill appear-'at the output of, the amplifier 24.V The phase detector 39'7Will produce a large output'if high level energy `is )Oeingreceived` anda small ,output if less energy is being received.

It is to be realized .that the lsignal received through the lead v31 Vis in phase with thereceived signal.

.The integratingnetwork-AI smooths the output of the phase detector 39 ,to produce a .substantially l. direct .currentsgnal lwhich is {trans- .initted to .the amplitude ,meter 42. f It I is 'calibrated so that its indicatorfgives a readngploportional to the amplitude ofthe receivedenergy. Whenasignal of vsuii'ici'ent..strength is` being received by the antenna' the amplifieiiand'integrator 43 willproducea ,direct currentsignal of sufficient 4strength toenergize therelay 4 6, thus connecting the switch 41 to the contact 49.

.Thesecond phase-.detector A3,8. receives inputs from the ampliiier'taiid thejreferencf generator 13,4.' The input furnished @byA lead. 3 6.' is shifted 90 degrees to the input furnished to phase de-A tector 39 and .will produce an output characterf isticproportional to the error in azimuth. `Zin other Words, if the center of .the antennascan isfocused on the; target, tlief Output 'of thefphase detect@ tmwillbe zeroywler' if.- the 'target is to" ethersdeorthej center or :the an enna. It

4 an output signal will be obtained with the polarity indicating the direction of deviation from center.

The second integrating network 5I smooths iiuctuations in the output of the phase detector 38. The output of network 5| is furnished through the contact 49, switch 41, contact 53, and switch v51 to servo amplifier 58.

The servo ampliier 58 supplies an input to the servo tracking motor 5l Which controls the aziimuth position of the antenna. Thus, if the output of the phase detector 38 is other than zero, itmeansthat an error in azimuth exists and this signal vwill .be :furnished to the servo tracking motor-Which Will vary the azimuth position untl thefazimuth'error has been corrected.

Thus, the .output shaft 62 of the servo tracking motor indicates the correct azimuth position at all-times. A one-speed synchro generator 63 is connected to shaft 62-and produces three electrical `outputsylhich are connected to a synchro motor.61 Whose armature Will track the armature'oi the synchro generator.

The output shaft (i8 is connected to the armature of motorv 61 ,and controls an azimuth indicator 69 which continuously gives an azimuth indication ofthe target.

The operationabove described has assumed that the antenna IWas intercepting a target. Howeven at certaintimes notarget Will be intercepted by the antenna .and atsuchtimes the output ofthe ,phase detectorV 33 .will be zero which will vbe indicated onthe amplitude meter 42 and which will cause the relay 46 to remain un-energized, causing the switch `41 to engage. contact .48. This connects .the 'sector scan signal generator `52 Ato theservo tracking motorl so that the `Signal `produceclby the gcnerator-52 will determine the positionnf, theantenna I0.

The sectorwscan .signal generator 52 may be any one of `anurnber oapparatuses. For example, itmaylbe ,a sawtoothgenerator `which produces as aw'toothwavethat will cause the antenna tosearch over a .ninety degree sector .or any other angular sector which may be adjustable. It may, on-the other` hand, produce a constant `direct currentoutput which will causeantenna l0 to continuously 'rotate in one direction until a target is intercepted. Whatever the form of` the signal generator Y52, it -Will be disconnected Whenever a target is intercepted whichproduces suflctpt radiant energy tov cause theoutput of the phase detector`39 ,to energize the relay 46. At that time vthe Asignal generatorr52 is disconnected and the4 phase detector ,38 takes control of the azimuth positionofv the antenna. The generator .5,2 might be `a square Wave generator tvhichlwould causetlie antenna to reverse direction everytime the polarity of fthe pulse changed. The manual control 56y is provided in the event that manual tracking is desired, at which time the switch .51 .will be manually moved to engage contact 54. The manualcontrol maf: comprise a battery or ,other voltage source Which may be varied'so as.A to furnish a varying cent1-ol signal tothe moto-riti `thfriiugll@theservo amplifier' 53;

'.Itisiseen, therefore, that this invention provides a means for continuously tracking a target or other body which isl producing a radiant energy output and wherein the amplitude of the radiant energy yand azimuth Willbe indicated. It

tvo pe lljlali'zgd thai-, scanning of the antenna A45 69 due to' the integrationnetwo'rk''ll Neither will uctuations in-amplitudebeindicated, due to integration bythe integrating network 4I.

Advantages of this system are:

1. Longer integration times in the output presentation could be used.

2. Temperature stabilization of the receiver Awould be eliminated.

3. The critical waveguide modulator would be eliminated.

4. Effects of a lumpy atmosphere absorption Would be minimized along with the effects of a non-homogenous radome.

5. The output resulting from radiation from the ground Would be minimized and wouldv be reduced essentially toy zero for a level horizon.

6. No nullifying voltages would have to be used.

7. The antenna could be made to automatically track the cloud. l v

8. The equipment could operate unattended.

Although this invention has been described with respect to particular embodiments thereof, it is not to be so limited as changes and modifications may be made therein which are within the full intended scope of the invention as defined by the appended claims.

I claim:

1. An automatic tracking means comprising, an antenna mounted on horizontal and vertical shafts, a radiometric receiver receiving the output of said antenna, a diiferential connected to one of the antennas shafts, an oscillatory shaft connected to said dierential, a rocker arm attached to said oscillatory shaft, a wheel supported for rotary motion, a link connected to said wheel adjacent the periphery and to said rocker arm, a scanning motor connected to said Wheel to rotate it, a pair of phase detectors receiving the output of said radiometric receiver, a two-phase generator producing outputs ninety degrees out of phase supplying inputs to said first and second phase detectors, a one to two step-up gear box connected to said scanning motor and to said two-phase generator, an amplitude indicator connected to the rst phase detector, a servo tracking motor supplying a shaft input to said differential and receiving an input from said second phase detector.

2. An automatic tracking mechanism comprising, an antenna mounted on a control axis, a radiometric receiver connected electrically to said antenna, a differential connected to said control shaft, a scanning motor coupled to said differential and providing an oscillatory shaft input, a tracking motor coupled to said differential, a two-phase reference generator connected to said scanning motor, a pair of phase detectors receiving inputs respectively from said two-phase reference generator, said radiornetric receiver supplying inputs to the first and second phase detectors, an amplitude indicating means connected to the output of the rst phase detector, and said servo tracking motor connected to the output of the second phase detector.

3. An automatic tracking mechanism comprising, a radiometric antenna mounted on a control axis, a radiometric receiver receiving electrical input from said radiometric antenna, a mechanical differential connected to said control axis, a servo tracking motor supplying a shaft input to said differential, a scanning motor, a wheel rotatably connected to said scanning motor, a link pivotally connected to the periphery of said wheel, a support shaft, a rocker arm rotatably supported on said support shaft and its free end pivotally connected'to said link,`saidsupport shaft supplying an oscillatory input to said differential, a one to two step-up gear box connected to said scanning motor, a two-phase reference generator connected t'o the output shaft of said step-up gear box and producing a pair of outputs which are separated in phase by ninety degrees, a pair of phase detectors receiving inputs from said radiometric receiver, the rst and second phase detectors receiving, respectively, the first and second phases of said reference generator, an amplitude indicator connected to the first phase detector and the servo tracking motor connected electrically to the output of the second phase detector. Y

4. An automatic tracking mechanism compris'- ing, an antenna supported on a control shaft, a radiometric receiver receiving an electrical input from said antenna, a pair of phase detectors receiving the output of said radiometric receiver, a differential connected to said control shaft, a tracking motor supplying a shaft input to said differential, a rotary to oscillatory motion conversion unit supplying an input to said differential, a scanning motor connected to said conversion unit, a step-up gear box connected to said scanning motor, a two-phase reference generator connected to the gear box, said pair of phasel detectors receiving inputs from said two-phase reference generator, a first integrating network receiving the output of one of the phase detectors, an amplitude meter receiving the output of said first integrating network, a relay connected to said rst integrating network, a second integrating network connected to the other phase detector, and said second integrating network connected electrically to the servo tracking motor when the relay is energized.

5. An automatic tracking mechanism comprising, an antenna supported on a control shaft, a radiometric receiver receiving an electrical input from said antenna, a pair` of phase detectors receiving the output of .said radiometric receiver, a differential connected to said control shaft, a tracking motor supplying ya shaft input to said differential, a. rotary to oscillatory motion conversion unit supplying an input to said differential, a scanning motor connected to said conversion unit, a step-up gear box connected to said scanning motor, a two-phase reference generator connected to the gear box, said pair of phase detectors receiving inputs from said two-phase reference generator, a first integrating network receiving the output of one of the phase detectors,

" an amplitude meter receiving the output of said first integrating network, a relay connected to said rst integrating network, a second integrating network connected to the other phase detector, a sector scan signal generator connected to a rst contact of said relay, a second contact of said relay connected to said second integrating network, and a movable contact movable between the first and second contacts and electrically connected to said servo tracking motor.

6. An automatic tracking mechanism comprising, an antenna supported on a control shaft, a radiometric receiver receiving an electrical input from said antenna, a pair of phase detectors receiving the output of said radiometric receiver, a differential connected to said control shaft, a tracking motor supplying a shaft input to said differential, a rotary to oscillatory motion conversion unit supplying an input to said differential, a scanning motor connected to said conversion unit, a step-up gear box connected to said .27 seenaieetmotorsartwn: hasefreferenee. generator Connectedt ,th ear*boxrsadpair'ofrphase .detectorsrece gfmputsfromfisaid twovphasereferencegenerator, rst integrating network receiv-irig the;output` of one-of 4the phase detectors, anamplitudemeter receiving the output of said mst-integrating network, a relayconnected to saidfirst integrating network, a second integrating network connected to the other phase `detector, ar-sector scan signalgenerator connected to a first contact of Ysaid relay, .asecondcontact of said relay connected togsaid secondintegrating network, a movable Contact movable between the rst andsecond Y, contacts and electrically connected to said servo tracking motor, and means for indicating theshaft position of -said servo tracking motor to, givean azimuth indication.

7. An automatic tracking-mechanism `comprisingfan antenna supported on a controlshaft, a radiometric'receiver receiving an electrical input from said antenna, a pair,v ofvphase detectors receiving thecutput of said radiometric receiver, a` differential connected .to vsaid control shaft, a tracking motor supplying -a shaft input to said differential, a rotaryto oscillatory motoncon-v version unit supplying an input to said differential, ascanning motor -connected to said conversion unit, afstep-,up gear-box connected to said I8 scanning meten-atwo-phasereference, generator connected to thegear -boxsaid pair of phase detectors receiving inputsgfrom-said two-phase reference generator, ,a rst integrating network receiving the` output of one .of the phase detectors, an amplitude meter receiving the output of said first integrating network, Va relay connected to said first integrating network, a second integrating' network connected to the other phase detector, a sector scan signal generator connected tothe first contact of said relay, a second contact of said relayconnected to said second integrating network, a first movable rcontact movable between the iirst :and second contacts, a second switch comprising, third and fourth contacts and a second movable -contact,rthe third contact connectable with the first movable contact, a manual control connectedtoxthe fourth contact, and said second movable contact connected to said second =servo tracking motor.

RICHARD M. RINGOEN.

References Cited in the le of this patent UNYITEDSTATES PATENTS Number Name Date 2,412,612 Godet Dec. 17, '1946 2,446,024 Porter et al July 27, 1948 2,448,007 Ayres Aug. 31, 1948 

